Crossword Genius

I undermine supposedly healthy food description as all the same (9)

Ross

I believe the answer is:

identical

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'all the same' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

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(Other definitions for identical that I've seen before include "Like two peas in a pod" , "Impossible to tell apart" , "not distinguished" , "Selfsame" , "Indistinguishable" .)

I've seen this clue in The Irish Times.
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